Question

Determine the heat of reaction (ΔHrxn) for the reduction of acetaldehyde (CH3CHO) to ethanol (C2H5OH) by using heat of formation data:

Answer 1

Answer: The enthalpy of the reaction is coming out to be -111.6 kJ.

Step-by-step explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as
`\Delta H`

The equation used to calculate enthalpy change is of a reaction is:

`\Delta H_(rxn)=\sum [n* \Delta H^o_f_((product))]-\sum [n* \Delta H^o_f_((reactant))]`

The chemical equation for the reduction of acetaldehyde to ethanol follows:

`CH_3CHO(g)+H_2(g)\rightarrow CH_3CH_2OH(l)`

The equation for the enthalpy change of the above reaction is:

`\Delta H_(rxn)=[(1* \Delta H^o_f_((CH_3CH_2OH(l))))]-[(1* \Delta H^o_f_((CH_3CHO(g))))+(1* \Delta H^o_f_((H_2(g))))]`

We are given:

`\Delta H^o_f_((CH_3CH_2OH(l)))=-277.6kJ/mol\\\Delta H^o_f_((CH_3CHO(g)))=-166kJ/mol\\\Delta H^o_f_((H_2(g)))=0kJ/mol`

Putting values in above equation, we get:

`\Delta H_(rxn)=[(1* (-277.6))]-[(1* (-166))+(1* (0))]\\\\\Delta H_(rxn)=-111.6kJ`

Hence, the enthalpy of the reaction is coming out to be -111.6 kJ.